Portable alternating current inverter having reduced impedance losses

ABSTRACT

A portable power supply apparatus is provided having reduced impedance losses. The portable power supply apparatus is comprised of: a portable housing; a battery system residing in the housing; and an inverter circuit residing in the housing. The battery system generates a direct current (DC) voltage having a magnitude greater than or equal to a peak value of a desired alternating current (AC) voltage. The inverter circuit receives the DC voltage directly from the battery system, converts the DC voltage to an AC output voltage and outputs the AC output voltage to one or more outlets exposed on an exterior surface of the portable housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/917,128 filed on Nov. 1, 2010 now pending, which is acontinuation-in-part of U.S. patent application Ser. No. 12/037,290filed on Feb. 26, 2008 now pending. The disclosures of the aboveapplications are incorporated herein by reference in their entirety.

FIELD

The present disclosure relates to power supplies and more particularlyto a portable alternating current (AC) inverter having reduced impedancelosses.

BACKGROUND

Portable power supplies such as internal combustion engine (ICE)generators may be used to power remote devices. For example, portablepower supplies may be used at construction sites to power tools when noelectrical power is available. Typical portable power supplies, however,may be too heavy and/or may generate an insufficient amount of power.For example, a single worker may be required to transport a portablepower supply around a construction site and possibly between levels of abuilding (e.g., via a ladder). As the power generation of a portablepower supply increases, however, the weight also increases.Specifically, larger generating devices (e.g., engines/alternators) maybe required to provide adequate power to the point of use.

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

SUMMARY

A portable power supply apparatus is provided having reduced impedancelosses. The portable power supply apparatus is comprised of: a portablehousing; a battery system residing in the housing; and an invertercircuit residing in the housing. The battery system generates a directcurrent (DC) voltage having a magnitude greater than or equal to a peakvalue of a desired alternating current (AC) voltage. The invertercircuit receives the DC voltage directly from the battery system,converts the DC voltage to an AC output voltage and outputs the ACoutput voltage to one or more outlets exposed on an exterior surface ofthe portable housing.

According to other features, the portable power supply apparatus mayhave a weight and output electrical power at a power-to-weight ratiogreater than 50 watts (W) per pound. In other features, the portablepower supply apparatus may weigh between 20 and 50 pounds. In otherfeatures, the portable power supply apparatus may generate greater thanor equal to 1500 W of continuous power and/or greater than or equal to3000 W of peak power.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1A is a functional block diagram of a portable alternating current(AC) power supply according to the prior art;

FIG. 1B is a functional block diagram of a portable AC power supplyaccording to one implementation of the present disclosure;

FIG. 2A is a view of a portable AC power supply system according to oneimplementation of the present disclosure;

FIG. 2B is a functional block diagram of the portable AC power supplysystem according to one implementation of the present disclosure;

FIG. 3A is a schematic of an AC power supply module according to oneimplementation of the present disclosure;

FIG. 3B is a schematic of an AC power supply module having a clustercontrol architecture according to one implementation of the presentdisclosure;

FIG. 3C is a schematic of an AC power supply module having invertercontrol architecture according to one implementation of the presentdisclosure;

FIG. 4A is a schematic of an inverter according to one implementation ofthe present disclosure;

FIG. 4B is a schematic of an inverter according to anotherimplementation of the present disclosure;

FIGS. 5A-5D are graphs of various AC output power waveforms according tovarious implementations of the present disclosure;

FIG. 6A is view of the portable AC power supply system having a displayaccording to one implementation of the present disclosure;

FIG. 6B is a view of the portable AC power supply system having varioustransport features according to one implementation of the presentdisclosure;

FIG. 7A is a view of the portable AC power supply system having anexternal internal combustion engine (ICE) generator according to oneimplementation of the present disclosure;

FIG. 7B is a view of the portable AC power supply system having anintegrated ICE generator according to one implementation of the presentdisclosure;

FIG. 8 is a functional block diagram of an ICE generator according toone implementation of the present disclosure;

FIG. 9 is a functional block diagram of the portable AC power supplysystem having a direct feed-through of an external AC power sourceaccording to one implementation of the present disclosure;

FIG. 10A is a functional block diagram of the portable AC power supplysystem, the ICE generator, and a remote device, each having remotemonitoring and/or remote control features via radio frequency (RF)communication according to one implementation of the present disclosure;

FIG. 10B is a flow diagram of a method for remote monitoring and controlof the ICE generator according to one implementation of the presentdisclosure;

FIG. 11A is a functional block diagram of a plurality of portable ACpower supply systems capable of charging via a single ICE generatoraccording to one implementation of the present disclosure; and

FIG. 11B is a flow diagram of a method for monitoring and controllingcharging of a plurality of portable AC power supply systems according toone implementation of the present disclosure.

DETAILED DESCRIPTION

FIG. 1A illustrates a portable alternating current (AC) power supply 10according to the prior art. Specifically, portable AC power supply 10includes an AC to direct current (DC) charger 12 that charges a lowvoltage battery bank 14 via a power source. The low voltage battery bank14 supplies a low DC voltage to a low voltage DC to high voltage DCbooster 16. For example, the low voltage battery bank 14 may be a largelead-acid battery that supplies a low DC voltage of 12V or 24V. The lowvoltage DC to high voltage DC booster 16 boosts the low DC voltage to ahigh DC voltage. A high voltage DC to AC inverter 18 then converts thehigh DC voltage to a desired AC output voltage. For example, the desiredAC output voltage may be 120V.

A typical commercially available inverter 19 may include a combinationof the low voltage DC to high voltage DC booster 16 connected before thehigh voltage DC to AC inverter 18. In other words, the low voltage DC tohigh voltage DC booster 16 may operate continuously to boost the low DCvoltage to the high DC voltage. The low voltage DC to high voltage DCbooster 16 may require a large amount of current and will have largepower losses (i.e., P=I²×R). Therefore, larger/thicker components may berequired to decrease losses due to high impedance, which in turnincreases the weight of the portable AC power supply 10.

FIG. 1B illustrates a portable AC power supply 20 according to oneimplementation of the present disclosure. Specifically, portable ACpower supply 20 includes an AC to DC charger 22 that selectively chargesa high voltage battery bank 26 via a power source. In some embodiments,the portable AC power supply 20 may also include a high voltage DCbooster 24 between the power source and the high voltage battery bank 26when a voltage greater than the voltage supplied by the power source isrequired.

The high voltage battery bank 26 may include a plurality of batteriesthat collectively generate a high DC voltage. For example, the high DCvoltage may be greater than 178V. The plurality of batteries mayinclude, but is not limited to, lithium-based batteries, zinc-basedbatteries, and/or potassium-based batteries. In one implementation, forexample only, the high voltage battery bank 26 may include two banks ofbatteries connected in parallel, each bank having 60 lithium phosphatebatteries connected in series, the high voltage battery bank 26generating approximately 200V DC (e.g., 3.3V per cell×60 cells=198V). Ahigh voltage DC to AC inverter 28 then converts the high DC voltage to adesired AC output voltage. For example, the desired AC output voltagemay be 120V. Alternatively, for example, the desired AC output voltagemay be 240V.

The portable AC power supply 20 requires much less current to operatecompared to the continuously running low voltage DC to high voltage DCbooster 16 of FIG. 1A. Therefore, connectors and cables may bethinner/smaller, which in turn decreases the weight of the portable ACpower supply 20. For example, the portable AC power supply 20 may weighbetween 20 and 50 pounds. In some implementations, the portable AC powersupply 20 may weigh approximately 35 pounds.

Furthermore, the high voltage DC to AC inverter 28 is not a typicalinverter configuration as shown in FIG. 1A (i.e., booster→inverter).Rather, the high voltage battery bank 26 directly supplies the high DCvoltage to the high voltage DC to AC inverter 28. The portable AC powersupply 20, therefore, may generate more output power than typicalportable AC power supplies while weighing less than typical AC powersupplies. For example only, the portable AC power supply 20 may generategreater than or equal to 1500 watts (W) continuous power. Additionally,the portable AC power supply 20 may generate greater than or equal to3000 W of peak power. Therefore, the portable AC power supply 20 mayhave a power-to-weigh ratio of approximately 50 W per pound, and in someimplementations greater than 100 W per pound.

FIG. 2A illustrates an outer view of an example portable AC power supplysystem 40. The portable AC power supply system 40 includes an enclosure42 that houses an AC power supply module (not shown). The AC powersupply module within the enclosure selectively charges a battery systemvia the AC source connector and an external AC power source. The batterysystem provides a high DC voltage which is converted to a desired ACvoltage (e.g., 120V) by an inverter. Therefore, the AC power supplymodule is capable of providing AC power to remote devices while thebattery system has sufficient charge.

The enclosure 42 allows the system 40 to be portable. For example, theportable AC power supply system 40 may be transported around aconstruction site. The enclosure 42 further includes an AC sourceconnector 44 and outlets 46, 48 on its surface that interface with theAC power supply module. The AC source connector 44 (e.g., a standardthree prong plug) allows the portable AC power supply system 40 toconnect to an external AC power source. For example, the external ACpower source may be an internal combustion engine (ICE) generatorcapable of 1000 W output power and weighing approximately 35 pounds. Theexternal AC power source, however, may also be a different size/type ofgenerator, a standard wall outlet, a thermal diode, a fuel cell, a solarpanel, a wind turbine, etc. The outlets 46, 48 allow devices (e.g.,power tools) to receive AC power at remote locations. For example, theoutlets 46, 48 may be standard three prong outlets.

Referring now to FIG. 2B, a functional block diagram of the exampleportable AC power supply 40 is shown. The portable AC power supply 40includes the AC source connector 44, outlets 46, 48, and the AC powersupply module 50. The AC power supply module 50 includes a power supplymodule 52, a control module 54, a battery system 56, and an inverter 58.For example, the inverter 58 may be inverter 28 shown in and describedwith respect to FIG. 1B.

The power supply module 52 receives AC input (V_(IN)) from an externalpower source (e.g., ICE generator). The power supply module 52 convertsthe AC input into DC power to power the control module 54 and forrecharging the battery system 56. The control module 54 selectivelycontrols recharging of the battery system 56. More specifically, thecontrol module 54 enables charging of the battery system 56 when acharge level is less than a threshold. Similarly, the control module 54may disable charging of the battery system 56 when the charge level isgreater than a threshold to prevent overcharging. The portable AC powersupply 40, however, may also generate output power independently of anexternal power source (i.e., when not connected to an external powersource) using the battery system 56. Additionally, the battery system 56may include replaceable batteries. In other words, individual batteries,battery banks, or the entire battery system 56 may be removed and easilyreplaced with a fully-charged spare unit (i.e., “hot swappable”). Forexample, replaceable batteries may provide for extended operationwithout charging via an external AC source.

The battery system 56 supplies a DC voltage to the inverter 58.Specifically, the control module 54 controls discharging of the batterysystem 56 which supplies the DC voltage to the inverter 58. The inverter58 converts the DC voltage to a desired AC voltage to output via outlets46, 48. For example, the desired AC voltage may be 120V. The controlmodule 54 may also control operation of the inverter 58. For example,the control module 54 may control switching frequencies of the inverter58 thereby controlling a shape of the output waveform. The control ofthe inverter 58 is described in more detail later.

Referring now to FIG. 3A, an example of the AC power supply module 50 isshown. The battery system 56 includes a plurality of battery banksB₁-B_(N). Each of the battery banks B₁-B_(N) includes a battery cellB_(C), a switch B_(SR), a resistor B_(R), and a battery control moduleB_(CC). For example, the switch B_(SR) may be a semiconductor-basedtransistor. The resistor B_(R) may also be referred to as a currentsensor. The battery control module B_(CC) receives information from thecurrent sensor B_(R) to control switching of the switch B_(SR). Thebattery control module B_(CC), however, may also receive otherinformation, such as control signals from the control module 54 orinformation regarding other battery banks.

The power supply module 52 receives AC input from an AC source via theAC source connector 44. For example, the AC source may be a small ICEgenerator. Additionally, for example, the AC source connector 44 may bea standard three prong plug that connects to the AC source. The powersupply module 52 converts the AC input to DC power for powering thecontrol module 54 and for recharging the battery banks B₁-B_(N). Thecontrol module 54 controls the charging of the battery banks B₁-B_(N)via the DC power generated by the power supply module 52. Specifically,the power supply module 52 may provide DC power to current sourcesI₁-I_(N) which selectively supply current to the battery banks B₁-B_(N),respectively, based on control from the control module 54.

The control module 54 also controls discharging of the battery banksB₁-B_(N) to the inverter 58. The series connection between the batterybanks B₁-B_(N) allows the control module 54 to supply a high DC voltageto the inverter 58. Different numbers of battery banks may beimplemented depending on the application. Similarly, different numbersof battery cells may be implemented in the battery banks depending onthe application. The DC voltage supplied to the inverter 58, however,should be greater than a peak voltage of a desired AC voltage output. Inother words, for example, the DC voltage supplied to the inverter 58should be approximately 178V for a desired 120V AC output.

The inverter 58 converts the high DC voltage supplied via the batterycells B₁-B_(N) to an AC voltage. For example, the inverter 58 mayconvert the high DC voltage to 120V AC at a frequency between 50 and 60hertz (Hz). The inverter 58, however, may also convert the high DCvoltage to a different AC voltage having a different magnitude orfrequency. When generating 120V AC, the power output of the inverter 58may be greater than or equal to 1500 W continuous or 3000 W peak. Theoutlets 46, 48 may output the power generated by the inverter 58 to oneor more remote devices (e.g., power tools). For example, the outlets 46,48 may receive a standard three prong plug.

The control module 54 may also communicate with the inverter 58.Specifically, the control module 54 may monitor operation of theinverter. Based on the monitoring and/or other parameters (e.g., batterycharge level, current flow, etc.), the control module 54 may control theinverter 58. More specifically, the control module 54 may controlswitching in the inverter 58 to shape the AC sine wave approximationoutput by the inverter 58. In other words, the AC sine wave output bythe inverter 58 may be a square wave having a plurality of steps toachieve an approximate shape based on a desired amplitude and frequency.

For example, as the battery charge level decreases the control module 54may command the inverter 58 to increase the duty cycle of the inverter58 effectively “stretching” the AC sine wave. The purpose of stretchingthe AC sine wave is to maintain a desired root-mean-squared (RMS)voltage output by the inverter 58 while having a lower DC voltage inputto the inverter 58. Specifically, the control module 54 may increase aduty cycle of the inverter 58 to adjust the output AC sine wave tomaintain desired RMS accuracy.

FIG. 3B illustrates an example of the AC power supply module 50 having acluster control architecture. Similar to FIG. 3A, the power supplymodule 52 receives AC input power via the AC source connector 44. Forexample, the AC source connector 44 may be a standard three prong plugthat connects to an external AC source (e.g., an ICE generator). Thepower supply module 52 converts the AC input to DC power for powering acontrol module 54 and for recharging the battery system 56.

The battery system 56 is divided into a plurality of battery cellsB_(C). Specifically, the battery cells B_(C) may be grouped in clustersC₁-C_(N) each controlled by a cluster control module CCM₁-CCM_(N),respectively. For example, cluster C₁ may include four pairs of discretebattery cells B_(C) connected in parallel and four transistors T_(S)connected across the terminals of each pair of battery cells B_(C).While four pairs of battery cells B_(C) are shown connected in parallel,other numbers of battery cells and other configurations may beimplemented. The battery system 56 may also include diverting (i.e.,bypass) circuitry used for charge balancing. For example, the controlmodule 54 may control the diverting circuitry to bypass a batterycell/cluster when the corresponding charge level of a given cell/clusterexceeds a predetermined threshold.

The transistors T_(S) are controlled by a respective cluster controlmodule CCM₁-CCM_(N), hereinafter referred to as CCM. The cluster controlmodule CCM may control respective transistors T_(S) to preventovercharging of respective battery cells B_(C). Specifically, thecluster control module CCM may switch transistor T_(S) to shunt currentflow through transistor T_(S) effectively holding the voltage acrosscorresponding battery cells B_(C). Additionally, the cluster controlmodule CCM may communicate with the control module 54 to have thecontrol module 54 reduce a current supply I_(φ) to prevent overchargingof the battery cells B_(C).

The inverter 58 converts the high DC voltage supplied via the batterycells B_(C) to an AC voltage. For example, the inverter 58 may convertthe high DC voltage to 120V AC at a frequency between 50 and 60 hertz(Hz). The inverter 58, however, may also convert the high DC voltage toa different AC voltage having a different frequency. When generating120V AC, the power output of the inverter 58 may be greater than orequal to 1500 W continuous or 3000 W peak. The outlets 46, 48 may outputthe power generated by the inverter 58 to one or more remote devices(e.g., power tools). For example, the outlets 46, 48 may receive astandard three prong plug.

The control module 54 may also receive temperature measurements of thebattery cells B_(C). The temperature measurements may be generated by abattery temperature module 55. For example, the battery temperaturemodule 55 may include one or more temperature sensors that monitortemperature of one or more of the battery cells B_(C), respectively. Thecontrol module 54 may also communicate with the inverter 58 and sendcommands to control the inverter 58 as previously described with respectto FIGS. 2B and 3A and as further described later.

FIG. 3C illustrates an example of the AC power supply module 50 havingan inverter control architecture and other additional features. A linefilter 60 removes noise from AC input via the AC source connector 44. Arectifier 62 converts the filtered AC to DC. A power factor correction(PFC) module 64 maintains an input power factor close to unity for themost efficient utilization of the AC input. The PFC stage mayalternately be designed to directly produce/regulate the output DCcurrent to the appropriate voltage/current level. This constantcurrent/voltage output may be used to charge one or more of the batterybanks B₁-B_(N) and/or provide power to the inverter 58.

The PFC module 64 may interface with a solar panel via a solarconnection module 65. The solar panel may provide for solar charging ofthe battery system 56. For example, the PFC module 64 may include analgorithm for maximum power point tracking (MPPT) for operating thesolar panel. The MPPT algorithm, however, may be located and executedelsewhere such as in the solar connection module 65 or in an externalsolar panel control module (not shown). Specifically, the MPPT algorithmprovides for control of electrical operating points of photovoltaic (PV)modules in the solar panel to maximize capturing of solar power. The PFCmodule 64 may also interface with a wind turbine via a wind connectionmodule 67. The wind turbine may provide for wind-based charging of thebattery system 56. The PFC module 64 may also include additionalcomponents that perform other features described in detail later such asadjusting the input load.

The inverter 58 converts DC voltage received from the DC-DC converter 66and/or the battery banks B₁-B_(N) to an output AC voltage. For example,the inverter may generate a desired AC voltage having a magnitude of120V. The inverter 58 is controlled by an inverter control module 68.Specifically, the inverter control module 68 may monitor the peak of theAC voltage generated by the inverter 58 and control the inverter 58accordingly. For example, when the peak of the AC voltage generated bythe inverter 58 is less than the desired AC output voltage, the invertercontrol module 68 may increase a duty cycle of the inverter 58 tomaintain a desired RMS voltage. The inverter 58 may output the ACvoltage to a circuit breaker 72. The circuit breaker 72 may interruptthe flow of current to prevent damage to components connected viaoutlets 46 or 48. For example, the circuit breaker 72 may be aresettable circuit breaker. A diagnostic module 74 may includeadditional circuitry for providing current output information to theinverter control module 68 and/or a battery management module 70.

The battery management module 70 controls the battery system 56 whichincludes battery banks B₁-B_(N). The battery banks B₁-B_(N) may beconnected in series. The battery management module 70 also communicateswith the inverter control module 68. For example, the inverter controlmodule 68 may notify the battery management module whether the inverter58 is on or off, whether a load is connected to the inverter 58 viaoutlets 46 and/or 48, etc. Based on this information, the batterymanagement module 70 may turn off the DC-DC converter 66, request a lowcurrent output, or request a high current output.

The battery management module 70 may be connected to a display 80. Thedisplay 80 may provide information to a user. For example, theinformation may include, but is not limited to a charge level of thebattery system 56, a load connected to the system, an output voltage ofthe system, whether or not the system is connected to a charger, etc.The battery management module 70 may also be connected to aninput/output (I/O) port 84. For example, the I/O port may provide forconnection to a computer or other suitable device for softwareprogramming and/or downloading of data for analysis. Lastly, the batterymanagement module 70 may have security via a lock input 82. For example,the lock input 82 may require a user to verify his or her identity(e.g., a fingerprint) before using the system.

The system may also provide 12V DC power via an alternate outlet 90using the battery system 56 or AC source power (i.e., when AC sourcepower is connected). Specifically, a semiconductor switch 88 may be usedto switch between powering a 12V DC converter 89 from AC power or thebattery system 56. For example, the alternate outlet 90 may be acigarette lighter-type outlet. Another semiconductor switch 86 may bedisposed between switch 88 and the battery system 56. Switch 86 may becontrolled by the battery management module 70. For example, the batterymanagement module 70 may open switch 86 to prevent over-discharge of thebattery system 56.

A heat source 92 may be implemented for warming of the battery system56. For example, the heat source 92 may be heat tape or blankets.Warming the battery system 56 may allow operation during coldertemperatures. Similarly, a cooling source 93 may be implemented forcooling of the battery system 56. For example, the cooling source 93 maybe a fan. Cooling the battery system 56 may prevent overheating. Anauxiliary output 94 may provide for powering of audio/visual (A/V)devices such as a radio or a television. A charger module 96 may be usedto charge additional battery packs. For example, removable/swappablebattery packs from power tools may be charged via the charger module 96.Lastly, a lamp 98 may be implemented. For example, the lamp may includea bulb and a reflector disposed within a housing. The lamp 98 may beused to illuminate a work area.

FIG. 4A illustrates an example of the inverter 58 that may generate apure sine waveform as depicted in FIG. 5A. Specifically, the inverter 58may include a full H-bridge with a passive filtered output. A controlmodule 100 may control switching of four transistors via pulse-widthmodulated (PWM) control signals. For example, the control module 100 maycontrol the transistors such that a full positive battery voltage or afull negative battery voltage is applied to the output V_(OUT). Theoutput V_(OUT), however, is also filtered to smooth voltage steps andthus can be a pure sine wave. Specifically, the filter includes apassive LC filter that includes an inductor and a capacitor connected inseries with the output V_(OUT).

FIG. 4B, on the other hand, illustrates another example of the inverter58 that is capable of generating the square and modified squarewaveforms of FIGS. 5B-5D. The inverter 58 may be generally described asan H-bridge with a polarity inverter (i.e., two H-bridges havingopposing polarities). Specifically, the inverter 58 may include anisolated step-down converter module 120 having a voltage controlledoutput. The inverter 58 may also include a control module 110 whichreceives inputs from the inverter control module 68 and/or the batterymanagement module 70.

The control module 110 may switch various transistors connected to theDC input and/or the output of the step-down converter module 120. Forexample, the transistors may be insulated-gate bipolar transistors(IGBTs). Specifically, the control module 110 may switch the transistorsin a specific order to create a desired output AC waveform. The inverter58 may manipulate the shape of the output waveform as previouslydescribed herein to generate the waveforms depicted in FIGS. 5B-5D. Themodified sine wave of FIG. 5D represents an approximation of a desiredAC voltage resembling the pure sine wave of FIG. 5A.

Referring now to FIG. 6A, an example outer view of the portable AC powersupply system 40 is shown. Specifically, the system 40 may include theAC power supply module 50 as shown in and described with respect to oneof FIGS. 3A-3C. The enclosure 42 may further include a display 200 fordisplaying information about the system 40. In some embodiments, thedisplay 200 may be the display 80 of FIG. 3C. For example, the display200 may display information that includes, but is not limited to, acharge level of the battery system 56, a load connected to the system,an output voltage of the system, whether or not the system is connectedto a charger, etc.

FIG. 6B illustrates a side view of the system 40 having varioustransport features. For example, the system 40 may include a handle 210for carrying the system 40. Additionally or alternatively, for example,the system 40 may include a strap 220 for carrying the system 40. Forexample only, two straps 220 may be implemented to allow the system 40to be carried on one's back in compliance with the Occupational Safetyand Health Administration (OSHA) standards (e.g., transport up aladder). The system 40 may also include other suitable features forcarrying or transporting the enclosure, such as a cart, wheels, etc.

FIG. 7A illustrates an outer view of the system 40 connected to aninternal combustion engine (ICE) generator 250 via the AC sourceconnector 44. While an ICE generator 250 is shown, the system 40 mayalso be connected to another power source such as a fuel cell, a thermaldiode, a solar panel, a wind turbine, or a different type ofengine/generator. For example only, the ICE generator 250 may generateapproximately 1000 W of power and may weigh approximately 35 pounds. TheICE generator 250 may be also be carried or transported along with theenclosure 42 as shown in FIG. 7B. Alternatively, the two may be carriedseparately. For example, one person may carry the system 40 in one handand the ICE generator 250 in his or her other hand. The ICE generator250 may supply the power supply module 52 with the input AC voltage forrecharging the battery cells and/or powering the control module 54.

FIG. 8 illustrates an example of the ICE generator 250. The ICEgenerator 250 may include a fuel supply 260, a fuel level sensor 265, aninternal combustion engine (ICE) 270, an electric generator 280, and acontrol module 290. The fuel supply 260 supplies the ICE 270 with fuel(e.g., gasoline). The fuel level sensor 265 measures a level of fuelcontained in the fuel supply 260. The ICE 270 combines the fuel with airand combusts the air/fuel mixture within cylinders to generate drivetorque. For example, the ICE 270 may be started automatically usingsuitable systems such as a starter or an ignition module. The drivetorque generated by the ICE 270 is converted to electrical energy by thegenerator 280. The generator 280 may output the electrical energy as anAC voltage V_(OUT). The control module 290 controls operation of the ICEgenerator 250. Specifically, the control module 290 controls start/stopoperations of the ICE 270. Additionally, the control module 290 may alsomonitor the fuel level using the fuel level sensor 265. Furthermore, thecontrol module 290 may transmit operational information to othercomponents and/or receive commands from other components (described inmore detail below). For example, the control module 290 may transmit afuel level of the fuel supply 260 to other components such as the system40 or a handheld monitoring device (described in more detail later).

According to another feature, the system 40 may include a directfeed-through whereby the external AC power source is used as a mainsource of power. FIG. 9 illustrates an example of the portable AC powersupply system 40 having an AC power supply module 50 with a directfeed-through. Specifically, the external AC power source (e.g., a walloutlet or an ICE generator) provides power directly to the inverter 58while the battery system 56 is selectively used when the external ACpower source is insufficient or fails (e.g., a line dropout). Forexample, the control module 54 may monitor the external AC power source(e.g., via the power supply module 52) to determine when the external ACpower source is insufficient or has failed. The control module 54 maythen begin discharging the battery system 56 to power the inverter 58and any components connected to outlets 46, 48. Having the batterysystem 56 to power the inverter 58 during failure conditions providesfor seamless transitions between power sources (i.e., no power outages).

For example, the system 40 of FIG. 9 may be implemented as immediatebackup power in residential applications. The inverter 58 may alsosynchronize its output AC power with the external AC power.Specifically, the inverter 58 and the power supply module 52 maycommunicate to synchronize the output AC power to the external AC power.In other words, the output AC power of the inverter 58 may be in-phasewith the external AC source. Having the inverter 58 in-phase with theexternal AC source may also provide for seamless transitions when theexternal AC source fails and the battery system 56 is then used. Forexample, the inverter 58 may send messages to the power supply module 52requesting phase information of the external AC power, the power supplymodule may then send messages back to the inverter 58, and the inverter58 may then adjust a phase of the output AC waveform based on thereceived messages (including the requested phase information).

Additionally, a plurality of systems 40 may be connected in parallel toprovide increased power output. The outputs of each of the plurality ofsystems 40 may also be synchronized with each other to provide maximumpower output. For example only, two systems 40 may be connected inparallel to generate greater than or equal to 6000 W of peak power(i.e., 3000 W×2 systems=6000 W). In some implementations, one of theplurality of systems 40 may act as a master with the remaining systems40 acting as slaves (i.e., the master synchronizes the slaves to itsoutput). For example, one of the plurality of systems 40 (“a slavesystem”) may send messages to another one of the plurality of systems 40(“a master system”) requesting phase information of the output ACwaveform of the master system. The master system may then send messagesback to the slave system, and the slave system may then adjust a phaseof its output AC waveform based on the received messages (including therequested phase information). Therefore, the slave system maysynchronize its output to the output of the master system.

According to another feature, the system 40 may automatically adjust thecurrent drawn from the ICE generator 250. In an exemplary embodiment,the control module 54 may variably control the current supplied by acharging circuit to the batteries and thereby control the current drawnfrom the ICE generator 250. For example, the control module 54 maydecrease a current drawn from the ICE generator 250 when the input ACwaveform is sagging (i.e., drops below a threshold). In other words, thesystem 40 may decrease the current draw to prevent overloading of theexternal AC source (e.g., the ICE generator 250). For example only, ifthe ICE generator 250 is capable of generating 100 W and a standardcurrent draw of the system is 1.5 amps (A), the charge range of thesystem 40 will be between 300 and 400 W (i.e., ˜180 V×1.5 A=360 W).Therefore, if not limited, the current draw of the system 40 couldoverload and damage the ICE generator 250. These techniques formonitoring current draw and overload protection may be similarly appliedto other external AC sources such as a solar panel or a wind turbine.

Alternatively, the system 40 may transmit an inquiry to the ICEgenerator 250 as to how much power the ICE generator 250 can generate,and the system 40 may then adjust the current draw from the ICEgenerator based on the transmitted response from the ICE generator 250(described in more detail later with respect to FIGS. 10A-10B).Additionally, a user may manually adjust the current draw of the system40 from the ICE generator 250. For example, the user may control arotatable switch to select an input power to draw from the ICE generator(e.g., 250 W, 500 W, 750 W, 1000 W, etc.). The user may select an inputpower less than a maximum output power of the ICE generator 250 to allowthe ICE generator 250 to power other components.

According to another feature and as previously described, the system 40may also have remote monitoring and/or control features. For example, auser may be working via an extension cord at a location far from thesystem 40 or on a different level of a building. Therefore, remotemonitoring may allow the user to determine, for example, when the chargelevel of the battery system 56 is low. Additionally, remote control ofthe system 40 may also be beneficial. For example, when the charge levelof the battery system 56 is low the user may remotely activate the ICEgenerator 250 to begin recharging the battery system 56. Accordingly,remote monitoring and control of the system 40 may increase userefficiency which in turn may reduce costs.

FIG. 10A illustrates a functional block diagram of the system 40, theICE generator 250, and the mobile device 300. The system 40, the ICEgenerator 250, and the mobile device 300 are each capable ofcommunicating via a radio frequency (RF) communication channel. Forexample, these components may communicate via the RF channel accordingto a suitable IEEE communication protocol (e.g., Bluetooth). The system,the ICE generator 250, and the mobile device 300, however, may alsocommunicate using other suitable wireless communication methods and/orprotocols. While each of the system 40, the ICE generator 250, and themobile device 300 are shown to include two modules, each may furtherinclude additional modules or components such as those described herein.

Specifically, the system 40 may include a communication module 305 thatmay transmit information (e.g., using a transceiver) to the mobiledevice 300 via the RF communication channel. For example, theinformation may include, but is not limited to, a charge level of thebattery system 56, a load connected to the system, an output voltage ofthe system, whether or not the system is connected to a charger, etc.Additionally, for example, the system may transmit fault conditions tothe mobile device. The transmitted information may be received (e.g.,using a transceiver) by a communication module 310 in the mobile device.The received information may be sent to a user interface module 320which may then display the information to the user (e.g., via thedisplay 275). In other words, the user may be located at a remotelocation with respect to the system 40 but may still monitor the system40.

The user may also input commands (e.g., via a touchpad) to the userinterface module 320. The user interface module 320 may send thecommands to the communication module 310 for transmission back to thesystem 40. In other words, the user may command the ICE generator 250via the mobile device 300. For example, the user may start the ICEgenerator 250 when the charge level in the battery system is less than afirst level (e.g., a critical threshold corresponding to the peak of thedesired AC output). Similarly, for example, the user may stop the ICEgenerator 250 when the charge level of the battery system 56 is greaterthan or equal to a second level (e.g., full charge).

The commands for the ICE generator 250 may be sent by the user (a“manual command”) using the mobile device 300 and relayed to the ICEgenerator 250 by system 40. Additionally or alternatively, the system 40may automatically send a command (an “automatic command”) to start/stopthe ICE generator, such as when the system detects that the charge levelof the battery system is less than a threshold. When the ICE generator250 receives a command via communication module 330, the communicationmodule 330 may send the command to the control module 290. The controlmodule 290 may then start or stop the ICE generator 250 based on thereceived command. The control module 290 may also include sensors formeasuring operating parameters. For example, the control module 290 mayuse the fuel level sensor 265 to measure an amount of fuel in the ICEgenerator 250 for transmission to the system 40 and/or the mobile device300.

FIG. 10B illustrates a method for remote control of the ICE generator250. While only remote control of the ICE generator 250 is described,other monitoring and control function may be implemented viacommunication across the RF communication channel. For example, themobile device 300 may be used by a user for remote monitoring and/orcontrol of the system 40 and/or the ICE generator 250. For example, themethod may be executed by the control module 54. The method begins at350. At 350, the control module 54 determines whether a command has beenreceived to start/stop the ICE generator 250 (“a manual start/stop”).For example, the user may input the command to the user interface module320 of mobile device 300 which may then transmit the command to thecontrol module 54. If true, the control module 54 may proceed to 358. Iffalse, the control module 54 may proceed to 354.

At 354, the control module 54 may determine whether any fault conditionsare present that require a start/stop operation of the ICE generator 250(“an automatic start/stop”). For example, the control module 54 maydetermine whether a fuel level of the ICE generator 250 is less than apredetermined threshold. Alternatively, for example, the control module54 may determine whether a charge level of the battery system 56 is lessthan a predetermined threshold. In some embodiments, the fuel level maybe transmitted to the control module 54 by the ICE generator 250 (e.g.,in response to a query). If true, the control module 54 may proceed to358. If false, the control module 54 may return to 350 (i.e., no manualor automatic start/stop operations).

At 358, the control module 54 transmits a command to communicationmodule 330 to start/stop the ICE generator 250. At 362, the controlmodule 290 determines whether the transmitted command was received(e.g., via communication module 330). If true, the control module 290may proceed to 366. If false, the control module 290 may return to 362.At 366, the control module 290 may start/stop the ICE generator 250according to the received command. For example, the control module 290may start/stop the ICE 270 via a starter or ignition module (previouslydescribed). The method may then return to 350.

According to another feature, the user may plug one or more portable ACpower supply systems 40 into a single ICE generator 250 if more than oneportable AC power supply system is needed at a jobsite. In a typicalsituation, an unequal amount of power may be drawn from these portableAC power supply systems. As an example, the user may plug two portableAC power supply systems 40 into the same ICE generator 250 for charging.FIG. 11A illustrates an example implementation of a system 400 having Nportable AC power supply systems 40-1, 40-2, . . . , 40-N (collectivelyreferred to as “systems 40”) connected to a single ICE generator 250.

For example, portable AC power supply system 40-1 may have two powertools plugged into it that draw an average load of 2000 W. Since the ICEgenerator 250 can only supply a limited amount of charging power, theICE generator 250 may not be able to charge all the systems 40 at fullpower. If each of the systems 40 monitors its own load and batterysupply, the systems 40 can collectively determine which of the systems40 should receive charge current and control their own chargingaccordingly. The following example shows how the inverters may decidehow to control their individual charge.

If system 40-2 is merely powering a light load (e.g., a light source)and has only ½ of its battery charge remaining, and system 40-1(powering the large load power tools) still has ¾ of its chargeremaining, the ICE generator 250 would ordinarily deliver more or anequal amount of power to the system 40-2. However, since system 40-1 issupplying far more power, the battery in system 40-1 will run out ofcharge much sooner than system 40-2. In the improved cooperativescenario, since system 40-2 can calculate its own remaining runtime anda remaining runtime of system 40-1, system 40-2 will choose to foregocharging so that system 40-1 can receive all of the power from the ICEgenerator 250. This allows the systems 40 to optimize runtime of theentire system 400.

FIG. 11B illustrates a method for monitoring and controlling charging ofa plurality of systems 40. For example, the method may be executed byone of the control modules 54 located in the various systems 40. Themethod begins at 450. At 450, the control module 54 may determinewhether a predetermined time has expired. For example, the controlmodule 54 may determine whether a timer exceeds a predetermined time of100 milliseconds. If true, the control module 54 may proceed to 454. Iffalse, the control module 54 may return to 450. At 454, the controlmodule 54 may send its current draw (from the ICE generator 250) and itsremaining capacity (in its battery system 56) to other the system(s) 40.At 458, the control module 54 may retrieve the current draw andremaining capacity from the other system(s) 40. At 462, the controlmodule 54 may calculate an average current draw of the other system(s)during a period. For example, the period may be one minute. At 466, thecontrol module 54 may calculate a remaining runtime of the othersystem(s) 40 by dividing remaining capacity by average current draw.

At 470, the control module 54 may monitor its own current draw andremaining capacity. At 474, the control module 54 may calculate itsaverage current draw during a period (e.g., one minute). At 478, thecontrol module 54 may calculate its remaining runtime (e.g., remainingself capacity/average self current draw). At 482, the control module 54determines whether its remaining runtime is less than the remainingruntime(s) of the other system(s) 40. If true, the control module 54 mayproceed to 486. If false, the control module 54 may proceed to 490. At486, the control module 54 may draw all of the current from the ICEgenerator 250 to charge its battery system 56. The method may thenreturn to 400. At 490, the control module 54 may disable charging of itsbattery system 56. All of the current from the ICE generator 250 maythen be used to charge a battery system 56 of the system 40 having theshortest remaining runtime. The method may then return to 400.

In the previous examples, the systems 40 either chose to receive fullcharge or no charge. An alternative embodiment would allow the systems40 to variably control the amount of current they each receive.Referring again to FIG. 11A, system 40-2 may calculate that in order toallow itself and system 40-1 to run out of power at the same time (thusoptimizing runtime of the system 400), that system 40-2 should receive10% of the charging power to allow system 40-1 to receive 90% of thecharging power. In some implementations, each of the systems 40 may varyan amount of charging power received from the ICE generator 250 bycontrolling respective internal charging circuits to vary charging ofthe respective battery systems 56. Lastly, while examples power controldistribution between two of the systems 40 were described herein, thesame examples may be similarly applies to three or more of the systems40.

The description herein is merely illustrative in nature and is in no wayintended to limit the disclosure, its application, or uses. For purposesof clarity, the same reference numbers are used in the drawings toidentify similar elements. As used herein, the phrase at least one of A,B, and C should be construed to mean a logical (A or B or C), using anon-exclusive logical or. It should be understood that steps within amethod may be executed in different order without altering theprinciples of the present disclosure.

As used herein, the term module may refer to, be part of, or include anApplication Specific Integrated Circuit (ASIC); an electronic circuit; acombinational logic circuit; a field programmable gate array (FPGA); aprocessor (shared, dedicated, or group) that executes code; othersuitable components that provide the described functionality; or acombination of some or all of the above, such as in a system-on-chip.The term module may include memory (shared, dedicated, or group) thatstores code executed by the processor.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared, as used above, means that some or allcode from multiple modules may be executed using a single (shared)processor. In addition, some or all code from multiple modules may bestored by a single (shared) memory. The term group, as used above, meansthat some or all code from a single module may be executed using a groupof processors. In addition, some or all code from a single module may bestored using a group of memories.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification, and the following claims.

What is claimed is:
 1. A portable power supply apparatus comprising: aportable housing; at least one battery generating a direct current (DC)voltage having a magnitude greater than or equal to a peak value of adesired alternating current (AC) voltage; and an inverter circuitcoupled to the at least one battery to receive the generated DC voltage,convert the generated DC voltage to an AC output voltage and output theAC output voltage to one or more outlets of the portable housing.
 2. Theportable power supply apparatus, as recited in claim 1, wherein the atleast one battery generates a DC voltage having a magnitude greater than150 volts (V).
 3. The portable power supply apparatus, as recited inclaim 1, wherein the inverter circuit modifies a waveform of the ACoutput voltage when the at least one battery generates a DC voltagehaving a magnitude less than the peak value of the desired AC voltage.4. The portable power supply apparatus, as recited in claim 3, whereinthe inverter circuit increases a duty cycle of pulse-width modulated(PWM) signals that control switching in the inverter circuit to maintaina root-mean-square (RMS) of the AC output voltage greater than or equalto an RMS of the desired AC voltage.
 5. The portable power supplyapparatus, as recited in claim 1, further comprising a power supplymodule configured to receive an AC input signal from a power sourceexternal to the housing, the power supply module provides a chargingcurrent to the at least one battery.
 6. The portable power supplyapparatus, as recited in claim 5, further comprising a control moduleconfigured to monitor a charge level of the at least one battery andselectively control the power supply module to charge the at least onebattery.
 7. The portable power supply apparatus, as recited in claim 5,wherein the power supply module includes a battery charge circuitelectrically coupleable to an AC power plug.
 8. A portable power supplyapparatus comprising: a portable housing, the housing having an exteriorsurface, the exterior surface having at least one outlet for providingan alternating current (AC) output voltage; a battery system having atleast one battery, wherein the at least one battery generates a directcurrent (DC) voltage having a magnitude greater than or equal to a peakvalue of the AC output voltage; and an inverter circuit configured toreceive the generated DC voltage having the magnitude from the at leastone battery and convert the generated DC voltage having the magnitude tothe AC output voltage.
 9. The portable power supply apparatus, asrecited in claim 8, wherein the portable power supply apparatus has aweight and outputs electrical power at a power-to-weight ratio greaterthan 50 watts (W) per pound.
 10. The portable power supply apparatus, asrecited in claim 8, further comprising a power supply module residing inthe housing, the power supply module configured to receive an AC inputsignal from a power source external to the housing and provide acharging current to the at least one battery.
 11. The portable powersupply apparatus, as recited in claim 10, further comprising a controlmodule configured to monitor charge level of the at least one batteryand selectively control the power supply module to charge the at leastone battery.
 12. The portable power supply apparatus, as recited inclaim 8, wherein the inverter circuit modifies a waveform of the ACoutput voltage when the at least one battery generates a DC voltagehaving a magnitude less than a peak value of the desired AC voltage. 13.The portable power supply apparatus, as recited in claim 12, wherein theinverter circuit increases a duty cycle of pulse-width modulated (PWM)signals that control switching in the inverter circuit to maintain aroot-mean-square (RMS) of the AC output voltage greater than or equal toan RMS of the desired AC voltage.
 14. The portable power supplyapparatus, as recited in claim 8, wherein the at least one batteryincludes one or more replaceable battery units, the replaceable batteryunits each having a storage capacity less than or equal to the storagecapacity of the battery system.
 15. A portable power supply apparatuscomprising: a portable housing; a battery system comprising at least onebattery coupleable to the housing, the at least one battery generating adirect current (DC) voltage having a magnitude greater than or equal toa peak value of a desired alternating current (AC) voltage; and aninverter circuit residing in the housing, the inverter circuitconfigured to receive the generated DC voltage having the magnitude fromthe at least one battery, convert the generated DC voltage to an ACoutput voltage and output the AC output voltage to one or more outletsexposed on an exterior surface of the portable housing.
 16. The portablepower supply apparatus, as recited in claim 15, wherein the at least onebattery generates a DC voltage having a magnitude greater than 150 volts(V).
 17. The portable power supply apparatus, as recited in claim 15,wherein the inverter circuit modifies a waveform of the AC outputvoltage when the at least one battery generates a DC voltage having amagnitude less than the peak value of the desired AC voltage.
 18. Theportable power supply apparatus, as recited in claim 17, wherein theinverter circuit increases a duty cycle of pulse-width modulated (PWM)signals that control switching in the inverter circuit to maintain aroot-mean-square (RMS) of the AC output voltage greater than or equal toan RMS of the desired AC voltage.
 19. The portable power supplyapparatus, as recited in claim 15, further comprising a control moduleconfigured to monitor a charge level of the at least one battery andselectively control the power supply module to charge the batterysystem.
 20. The portable power supply apparatus, as recited in claim 15,wherein the power supply module includes a battery charge circuitelectrically coupleable to an AC power plug.